Threadgrass is a small bunchgrass to 2 1/2 ft. with silvery seed heads all season above fine chartreuse leaves. Full but graceful. Fast growing & can spread from seed.   Can be summer deciduous if temperatures are hot, or if kept dry. Sways in the wind; reminiscent of eastern beach grasses. Likes medium water to drier conditions.  Likes full sun but can tolerate some shade.